Calcium isolation from large-volume human urine samples for 41Ca analysis by accelerator mass spectrometry

• A method was optimized to precipitate calcium oxalate from large-volume urine samples.
• The modified protocol resulted in AMS measurements with significantly higher ion current and decreased interference.
• Result is lower effort and cost and higher sensitivity for bone remodeling studies.

Calcium oxalate precipitation is the first step in preparation of biological samples for 41Ca analysis by accelerator mass spectrometry. A simplified protocol for large-volume human urine samples was characterized, with statistically significant increases in ion current and decreases in interference. This large-volume assay minimizes cost and effort and maximizes time after 41Ca administration during which human samples, collected over a lifetime, provide 41Ca:Ca ratios that are significantly above background.